The invention relates to a device for measuring forces by means of at least one anti-friction bearing, the outer ring and/or inner ring of which are or is provided with strain gauges arranged at different measurement points, which serve to detect overroll extensions, whilst at least two strain gauges are connected as a half-bridge in each case.
Devices of the above type with three, four or more strain gauges are known from German Patent No. 2,911,479. In the known devices, strain gauges are used which are all adapted to a material with the same coefficient of expansion, that is to say, in practice are tuned to an anti-friction bearing steel, particularly 100 Cr 6. The reason for this type of choice of the strain gauges is that when measuring forces it is generally desired to keep temperature-dependent influences upon the measurement signal small, and it was believed that this aim could be attained only by the use of strain gauges adapted to a material with the same coefficient of expansion. In cases where it was required additionally to measure the temperature of the anti-friction bearing, additional temperature sensors, for example in the form of stick-on thermo-elements, which increased the manufacturing outlay for the measuring apparatus, were employed. The above-indicated evaluation of the situation, that is to say the view that particular temperature sensors are required with devices of the type stated in order to permit the bearing temperatures also to be detected, has proved to be incorrect. Starting from this discovery, the underlying aim of the invention is to produce a device of the category in question, with which it is possible to detect both forces influencing the bearing and also the temperatures prevailing in the bearing without recourse to additional temperature sensors, that is to say solely by the use of strain gauges.